Mobile AddON needed or not?

I volunteer at an advice charity (free advice) and we are looking at buying a charity discounted teamviewer business license to allow some of our advisers to connect to a client's mobile phone, tablet or computer so that we can watch them going through the process of applying for benefits or government grants online and offer advice about how to complete the application correctly.

The model would be that we ask the client to download and install quick connect or teamviewer and we then make a conection so that we can see what the client is doing  and assist them to answer the application questions as they go along.

I'm not clear whether we would need to purchase the Mobile AddOn or not as none of our team would be using a mobile device - we would all be using teamviewer on desktop machines.

Can someone please advise whether we would need the AddOn for our use case? This license adds quite a lot of cost to the purchase even at charity prices.

Many thanks.